1. Field of the Invention
The present invention relates to a cleaning unit for a roller member supporting a belt that cleans a roller member supporting a belt member driven in an electrophotographic copier or printer that obtains an image by using the belt member and an image forming apparatus.
2. Description of the Related Art
Recently, there is known a tandem system image forming apparatus (copier, printer, or the like). In the tandem system image forming apparatus, a plurality of photoconductor drums are arranged in a line, toner images formed on the respective photoconductor drums are multiply-transferred onto one sheet of paper and, thereby, one color image is obtained. Some image forming apparatuses of this type include an intermediate belt unit, wherein the toner images formed on the respective photoconductors are primary-transferred onto an intermediate transfer belt and, after that, the primary-transferred color toner image on the intermediate transfer belt is secondary-transferred onto a sheet of paper at a time; and others include a conveyor belt unit, wherein the toner images formed on the respective photoconductors are directly transferred onto a sheet of paper conveyed by a conveyor belt.
The belt member such as the intermediate transfer belt unit or conveyor belt unit disposed opposite to a plurality of photoconductors is generally stretched over a plurality of rollers. In the image forming apparatus, toner is dispersed at the development or transfer time, or paper powder is caused at the transfer/peeling time. The dispersed toner or paper powder may be adhered to the surface of the belt member. Further, the dispersed toner or paper powder may be introduced inside the belt member and adhered to the back surface of the belt member and rollers that stretch the belt member. When the dispersed toner or paper powder is adhered to the rollers or the back surface of the belt member, for example, when they are adhered to a drive roller, the rotation speed of the belt member becomes unstable, which may lead to image degradation. Further, there is a fear that dispersed toner or paper powder that has been adhered to a plurality of rollers scratch the belt member to cause breaking of the belt.
In light of the above, Jpn. Pat. Appln. Laid-Open Publication No. 2001-192136 discloses an apparatus that includes a roller cleaning member for cleaning the back surface of a conveyor belt or intermediate transfer belt and the front surface of a drive roller for driving these belts.
In this conventional cleaning unit, a cleaning member such as a felt, adhesive rubber, acrylic brush, or fur brush is directly attached to a fixed supporting member. That is, the cleaning member is pressed to the drive roller by the fixed supporting member, increasing a load applied to the drive roller. Therefore, it is necessary to previously increase a torque for causing the drive roller to rotate the belt member in consideration of a load applied to the drive roller by the cleaning member. As a result, there occurs a need to increase a drive power of the drive roller for rotating the belt member as well as a need to increase the strength of the belt unit.
Thus, there is demanded development of a cleaning unit for a roller member supporting a belt capable of reducing a load applied to the roller member by the cleaning member for cleaning the roller that supports the belt member to thereby stabilize the rotation speed of the belt member as well as reducing a drive power for driving the roller member and an image forming apparatus mounting such a cleaning unit.